localvariable

A local variable is a variable that has been declared within a function, method, or block and is only accessible within that scope. It exists temporarily while the code that created it runs and is disposed of when that code finishes. In most procedural and object‑oriented languages, a local variable’s name cannot be seen or used outside its enclosing function, preventing accidental interference with variables of the same name elsewhere. Local variables are distinct from global or member variables, which have a broader scope.

The type of a local variable can be inferred in languages that support type inference, such as C# 3.0+ or JavaScript, or explicitly declared, as in Java, C++ or C#. The value stored in a local variable is typically held on the stack, though some languages may move it to the heap or store it in registers for optimization. Because of the stack storage, initialization is mandatory before use; accessing an uninitialized local variable is a compile‑time or runtime error.

Different languages impose constraints on local variables. For example, Java requires local variables to be formally initialized before reading their value, whereas Python does not have a static type system and allows dynamic assignment. In functional languages, local bindings created with let or where clauses are also local variables, but they are usually immutable by default.

Common pitfalls include mistaking a local variable for a global one, failing to initialize, or shadowing a global variable. Good practice is to keep local variables as small in scope as possible, name them clearly, and use immutability when safe.